Lithium soap grease containing basic alkaline earth metal sulfonate



Patented Sept. 16, 1952 'iiiTfiIUMsoAP eesAsE a anmmnnzmrn METAL summers i .ration-ofnelaware 'NoEDraWingr applicationFebruaryxgifii; I

swarm. aromas ia'iciaime. (01.:25242'22) This invention relates to .alithium :base; lubricating grease composition,-and particularly to such a composition which is inhibited against copper corrosion.

Lithium .base lubricating grease compositions have found substantial iuse-jin aircraft -.cntro1s and for other purposes where ,operation' over a wide temperature range, and particularly opera tion at extremely low temperatures, is encountered. U. S. PatentNo.450,221,AshburmBarnett and Puryeanis typicalaof alsuperior lithium base grease of this type prepared froma -lithium soap of a hydroxy fatty acidor atheglyceride thereof, such as hydrogenated ieastdr .oi1,-;an d containing as the major 'pr'oportionaof theliquid lubricating base an .oilsoluble highmolecular weight high boiling liquidialiphaticadicarboxylic acid ester within the lubricatingoil :viscosity range and possessing lubricating properties- As disclosed therein, theilithium-soapim'ay be formed from a major proportion of the hydroxy fatty acid or glyceri'de thereof and ia-minoraproportion of a saturated fatty acid, thefgreasezcontaining a small excess of free fatty acid. Such greases have exceptional shear and texture-stability over a wide temperature range and-exceilent glowltemperature properties.

While the lithium tbaselgreaisesrro'f zthesaioresaid type have proved eminently! satisfactory in serv ice, theincreaseduse of copper and coppen'alloys in certain applications',-iparticu1a;rty :aircrait controls, has introduced an additional zproblem of renderingv the 'greasesnon-icorrosive Ltd-copper in long time service; For thisrpurpose; :8. Army specification .2l34'has prescrihed: gor ous copper corrosion' test for qualificationiunder this specification, In attempting to meet" this specification, it has been found that corrosion inhibitors heretofore-employediinfgreases are ineffective.

One or theprinoipal .obiectszdf*therpresentainvention is to provide a, lithiumzhase greasezwhich satisfactorily meets the 00131381 COHOSiODQtESbiOf U. S. Army specificationr2- 134fl Another objectnoi the-present invention :is .to

provide a lithium base grease which retain a the desirable properties, ot the previously k'n greases= of this type;including shearaiidv ritur stability over a wide temperature range anaescellent low temperature properties", anapat the same timeis-efiectiyely inh cited-age ftcor sion ofaeopper rand -copper -.a-ll'oy .in rear tiin iy H' .1. ,1 v,

In accordance withth esent inventiofi, the foregoing objects have been-attained 'by iiicoi' porationin the lithium =base; grease,-abdut 0'525 V 3 by weight of an oil soluble basic all ralinezearth metal :sait-of .a sulfonated hydrocarbon wherein the weight ratio ofalkaline-earth metal to sulfur content-is from l .ltq;2 tin iies that iepr'eserited bf? the normal salt 1015033522, where is alkaline earth-.metal and R is the hydrocarbon residue. The foregoing-salt is to be distinguished from-the previously usednormal alkaline earth metal suifonates, such "as calcium im'aho'gafri s'ulfonate, which'latter have been found to b I ple qly ineffect've for urpdsesloritne pfsiitlifi vention The'basic-all zaiine earth mtal-s'ulfonateszwli" "h are effective copper corrosioni.inhihitirs for or poses of the; present invention, are known conipounds which have heretofore -been uggested along with the normalmahogany sulfonates as detergent additives :for liquid ,iubricamexsuen as motoroils iHpwever g -t ;was inotQt'o be' aritieipated that .theba-sic alkaline earth .niet'a'l smf onates weuld function as copper corrosion i1ihibitors-in-this different environment ran son base lubricating ,greasecomposition such -as';to pass the rigorous :copper-,corrosion test of the said 2-134 specification, particularly when ,thebetter known and more generally used mahogany sulfonates proved completely ineffective,forY-this purp e l, a

The basic sulfon'ates employed; in; accordance with thiswinvention may be prepared ioy :sulidna: tion of a lubricating oil stock or other mineral hydrocarbon oil, bycontacting with sulfuric acid of highaconcentration at'an elevated temperature .of the-Orde'rof 1-5.0-e18 0. F,,-,to produce sillbsta'fftiell 3 sulfonation without excessive loss to acid sludge. The resulting sulfonated oil, after separation of the acid sludge, may be reacted directly with powdered hydrated alkaline earth metal oxide in an amount substantially in excess of that required to neutralize the oil. Preferably, however, the basic sulfonate is formed by first purifying the sulfonated oil by neutralizing with sodium hydroxide, extracting the sodium sulfonate with an aqueous alcohol such as isopropyl alcohol, separating the aqueous alcoholic extract from the residual oil, precipitating the sulfonic acids by acidifying with sulfuric acid, filtering and forming a lubricating oil solution of the sulfonic acids, and finally reacting with an aqueous solution of a watersoluble alkaline earth metal salt. Thus, in preparing a basic barium sulfonate, an aque ous solution of barium chloride with the latter in substantial excess of that required for neusolution. The reaction mix is subjected to steam; j

V fish oils, or theindividual acids themselves. Very ing with agitation for a substantial period oftime, such as about 1-4 hours, to form the basic barium sulfonate, which is generally a'material of intermediate chemical composition between the truly basic barium sulfonate BaOHSOsR and 'the Following separation of the aqueous phase, the lubricatingv normal barium sulfonate Ba(SOaR)2.

oil solution of the basic barium sulfonate is washed and then heated to remove residual moisture to obtain a lubricating oil concentrate of the desired additive in about 2 -50% concentration. The basic salt of sulfonic acid may also be made by reacting an oil solution of the sulfonic acid with a methanol solution of the base (e. g. barium hydroxide) and then removing the methanol. In general, the weight ratio of alkaline earth metal to sulfur content in the desired material for purposes of the present invention will be in excess of 1.1 times that'represented by the normal salt M(SO3R): and up to two times that represented by the said normal salt. 1 V

While any of the alkaline earth metal basic salts of a sulfonated hydrocarbon, including those of calcium, strontium and magnesium, can be employed, the basic barium sulfonate is'pr'eferred. Moreover, while the hydrocarbon selected for sulfonation is generally a mineral oil fraction, particularly a lubricating oil distillate or solvent extract thereof, this is not essential. Other oil 501-- uble hydrocarbon sufonic acids suitable for preparing basic 'sulfonates of the present invention may be produced by sulfonating alkyl aromatic hydrocarbons, such as alkyl benzenes and alkyl naphthalenes, wherein the alkyl group or-groups in the side chains have at least about 8 carbon atoms and preferably more to provide 'oil solubility. Thus an alkyl aromatic hydrocarbon suitable for the production of the desired oil soluble sulfonic acids may be formed by condensation of aromatic hydrocarbons with chlorinated paraifin wax, alkyl chlorides such as chlorinated kerosene, polymerized olefins such as polypropylene, fatty alcohols etc. Suitable condensing agents are the Friedel-Crafts catalysts, sulfuric acid and the like. I

The above-described basic alkaline earth metal sulfonates may be employed in lithium base greases formed from any saturated fatty material, such as the conventional saturatedfatty acids or glycerides thereof, to provide copper corrosion inhibition.

Preferably, the lithium base greases formed from hydroxy fatty acids or their corresponding glycerides, such as hydrogenated castor oil are employed to obtain the improved shear and texture stability. Suitable types of soap-forming hydroxy fatty acids and glycerides thereof are disclosed in said Patent No. 2,450,221. While the soap-forming hydroxy fatty acids or their glycerides may be used as the sole acidic component of the lithium soap, they may be blended or combined with the conventional saturated fatty acids or fats in such proportions that at least 50% of the total acidic component is comprised of the hydroxy fatty acids or glycerides thereof. In general, any of the recognized fatty acid materials normally used in grease manufacture may be employed providing they are essentially saturated in character. These fats and fatty acids include mixtures of fatty acid 'glycerides found in naturally occurring fats and oils, together with fractionated components thereof. The fatty acids may be a mixture of acids split off from these fatsor-prepa-red from hydrogenation of of the lithium soap a mixture of about 60-80% of hydrogenated castor oil or IZ-hydroxy stearic 'acid'with 40-20%of a saturated fatty acid such as stearic acid. The grease may contain about 10-30% by weight of the lithium soap.

In order to obtain the improved wide temperature range and low temperature properties, the liquid lubricating base of the lithium grease compositionis preferably formed-0f a major propor-' tion of a synthetic oleaginous'lubricating compound or condensation product, many types of which are now known in the art. Very satisfactory synthetic'lubricants of this character are represented by thehigh moleculanweight high boiling liquid aliphatic dicarboxylic acid esters which are within the lubricating oil viscosity range andposse'ss' lubricating properties. 'The compounds within' this particular classare the esters of such acids as sebacid'adipic, pimelic, azelaeic, alkenyl succinic, alkylmaleic, etc. The esters thereof are preferably the aliphatic esters and particularly thebranched chain aliphatic diesters. Specific examples QfJt'ne preferred ole-' aginous compounds are. di-Z-ethyl' liex'ylseba'cate; di-Z-ethyl hexyl azelate, di-Z-etliyl'hexyl adipate, di-sec-amyl sebacate,i di-2-ethyl hexyl alkenyl succinate, di-2-ethoxyethyl -sebacate, di-2(2- methoxyethoxy) 'ethyl sebacate; di-'2-(2-ethyl butoxy) ethyl sebacate, di-2-butoxy'. ethyl azela'te, di-2-(2'-butoxy ethoxy) ethyl alkenyl succinate, e c. v

These oleaginous compounds maybe used as the sole oil component of the grease or they may be blended with a mineral lubricating oil. Where a blend is employed, and low temperature properties are required, the mineral lubricating oil is preferably a light refined distillatemineral lubricating oil, such as. a naphthene or paraffin base distillate, having an'SUS viscosity at F. of about 50-130'and preferably about 100 secs. The mineral'lubricating oil will generally constitute less than 50% of the blend, and ordinarily about 40-20% thereof. The mineral lubricating oil blend is advantageous where the lithium soap is formed in situ. In such case, thesaponification of the fatty material with the lithium hydroxide and dehydration of the resulting soap are conveniently carried out in the presence of .a portion of the mineral lubricating oil, and the synthetic lubricant together with the additives employed in the grease are then added following dehydra tion and as the agitated'soap mix cools.

followin examples are given to. illustrate hexyl sebacate with about 25% by weight of'a" naphthene base mineral lubricating oil having an SUS viscosity at 100 F. of about 50-60. The method of preparation involved charging a steam-heated kettle with the required amount of 10.3% lithium hydroxide solution. together with a small amount of water and heating to about 180 F. The hydrogenated castor oil was then added together with a small proportion of the naphthene base mineral lubricating oil, the latter being less than the amount of hydrogenated castor oil. The kettle contents were held. at 170-190 F. for about 4 hours while agitated, and then the stearic acid was added and the temperature maintained with stirring for another 1-2 hours to complete saponification. The saponif ed mix was then heatedv with stirring at. b u 2 3 o.r1 on 4 ou s to e t dehydration. I-heba'lance of the mineral lubricating-oilwas then added with stirring as the. kettle con-tents cooled down toabout 270 'F. Finally; the di-Z-ethyl hexyl sebacate-was' slowly added with stirring during further cooling, and any additives were then introduced into the rease before the latterwas drawn at a temperature below 200 F.

A series of greases were-prepared in the foregoing manner. to each of which was added about 0.5% by weight. of phen l alpha naphthylamine as an oxidation inhibitor, together with various additives f. t e co osio i hib ting. type. in an efiort to produce a grease meeting the copper o o on; st of h .34sneo cation The. consistencies of the various greases were ad-' justed' within the ball and roller bearing grease range, varying from a soap content of about 12.5% to about 18% by weight. As pointed out above, each of the greases had an approximately 3:1 weight. ratio of lithium soap of hydrogenated asto oi o li ium t ar t and had an ap-- proximately 3:1weight'ratio of diPZ-ethyl hexyl eb i te min rallu a ns o l. he in ow ns; T l' how t resu ts obtained on. thes greases in the, listed. 3-134- corrosion test. em-= moving the various dditives n the base grease an i igh percent s -1. t d .1nthetab1epressuredrop due-to.oxygenabsorption must occur. Then at the completion .of the -hour period, both the sample of grease and copper strip are inspected. In addition to the require- ..ment fo no pressure drop during the test. there must be no more than a very faint stain on the ooppe strip and no more thana slight stain on the grease in Order to be rated as passing.

. .Slightlrinferior products which do not merit a .l. .1'P.ass" ratingaregiven a rating of "borderine:to.pass" where there is no more than a light stain-onthe grease and no pressure drop; and

' a rating of borderline to fail" where there is a stain on the copper with or without a stain on the. grease and no pressure drop. All other aresuits arerated as ,faih 1 Since the foregoing greases. of Table I, in.- cluding the base. grease of sample: 1. which com tained 'nocorrosion inhibitor, all were compounded with about 0.5% byweight. of the effective oxidation inhibitor phenyl alpharraphthylamine, they all satisfactorily met the re quirement for no pressure drop during the test, and this item is not separately listed in the ab e, Itis to be noted. thatthe base. grease .of sample. ,1. produced a. light brown stain. on the copper strip while the. rease. was also slightly discolored. and thus failed the test. Sample 2 containing a combination of; 4.1% of;,tal1ow with 6.6%, of conventional. calcium. maho any sulfohate, which combination is recognized to be an SAMPLE 2',

A base grease'was. prepared in theforegoing manner of Example 1. and had the following cal- .culated composition;

. p V Weight-percent ith um oap of' hydrogenated caster Paraflin base mineral lubricating" 011" v having SUS at F. Of 'I0,2-l 18187.

Table I I 2-134Clltih5ion1 i ii i ew h B ton? r v Qopper Grease Result 1. blonelfln'n. Q ljightbrown 'dlightigdarker. Fail. 2; T?1lov%.'(4h1g/Z$-. I=Ca mahogany su1'- Greenish-brown: Darker; D0". 3. 13831 37? acid' orthophosphate Dari; brgwn Blackne ar cop-- Do; (g g ig-kgfl mahogany sulionate: per. 4. N imabogany sulfonate (2.7%}; do...,.. slizglitidiscoiora- Thea-13.4 corrosion test of the foregoing table p Di-Z-ethyi hex-yr sebacate 56131 wasrunby placing a copper stri -in a No mahenyI alpha naphthvlam ne- 0:372 Hoifman bomb so as to be partially immersed in Glycerin (from thefat-) 15, 3 a sample of the grease under test, and then Dye s 0 .00

maintaining the bomb under oxygen pressure pounds per square inch initial pressure)..' at

T0 the foregoing base' greaseg.various additives 21 0 F. for- 20 hours. Duringthat. neriodgno 75 were. added inthe. percentagesasshown in-the 7 following Table II, and the resulting grease samples tested in the 2-134 corrosion test with the indicated results:

8 free alkalinity in a lithium base grease containing a basic alkaline earth metal sulfonate of the present invention, the following Table III is Table II v l 2-134 CorrosionTest Additive Weight Percent I Copper Grease Result 1. None Light brown... Faint lavender Fail. r

. around copper. 2. Merciaptobenzothlazole .....do No change Do.

.2- r 3. N,N-disaliculidene-1,2 diami- .do Dark grey Dc.- nopropane (0.25%). 4. Alkyl Maieic Acid (0.25%) Dark brown Purple D0. 5. Sulfonated Tallow (0.5%)..-. Nont-iillliiform Lavender Do.

is a 6. 4-methy1 2,6-ditertiary butyl Dark brown Slightly darken. Do.

phenol (0.5%). 7. Ca phenol sulfonate (06%).... Unchanged Light lavender" Bordfeqme o a1. 8. Sorbitan mono-oleate (0.5%)... Light stain Unchanged Do- 9. Santolube 203A (1.23%)"--. Unchanged -d Pass. 10. "Santolube 203A (0.5%) Veryslightstain. Veryslightstain. Botrderlino 0 pass. 11. Santolube 203A (0.25%) .do Very slight dark- Borderline i ening. to fail.

Viscosity SUS at 210 F 55.5 Color Lovibond 1A in. cell 660.0

Chlorine, weight per cent 0.13 Sulfur, weight per cent 1.03 Barium, weight per cent- 4.15

As will be noted, the weight ratio of barium metal to sulfur content calculates to 4.03, as against a theoretical ratio for the normal barium sulfonate of 2.14 and for the completely basic barium sulfonate of 4.28. Other typical basic barium sulfonates tested, and which have been effective for purposes of the present invention have had weight ratios-of barium metal to sulfur contents of 3.27 and 2.69 respectively. In general, it can be stated that the weight ratio of alkaline earth metal to sulfur content in the effective materials may vary between about 1.1 up to two times the theoretical Weightratio for the normal salt. It thus appears that the truly basic compound-is not necessary, but a complex material which is basic in character so as to have a weight ratio of the alkaline earth metal to sulfur content which is in excess of 1.1 times the theoretical ratio for the normal salt, is satisfactory for purposes-of the present invention. These satisfactory materials are termed herein basic alkaline earth metal sulfonates.

Referring again to the foregoing Table II. sample 1 shows that the base grease fails the 2-134 corrosion test. Samples 2-8 show that various additives which are recognized as highly effective corrosion inhibitors in other environments, when added to the said base grease, failed to produce compositions which passed this rigorous test. On the other hand, samples 9-11 show that the basic barium sulfonate was unexpectedly effective in a proportion of about 0.25% and over in enabling the grease to pass this rigorous test.

EXAMPLE 3 In order to illustrate the effect of free acidity or H borderline in this test.

. tests, it can be stated that the grease of the listed. This shows the results obtained on 3:1 lithium soap of hydrogenated castor oil-lithium stearate greases containing 3:1 mixture of di-2- ethyl hexyl sebacate and paraflin base mineral lubricating oil, together with 0.5% phenyl alpha naphthylamine and 1% Santolube 203A (except that sample 5 contained 1.5% "Santolube 203A).

Table III rer en t ff: 2-134 ree 8 Y 3 Corrosion Acid as hnity 83 Oleic 1011 Test 1 Contains 1.5% of Santolube 203A."

, strict neutrality failed the test, and samples 4 and 5 which contained 0.1% free alkalinity were Sample 6, which was prepared to 0.2% alkalinity readily passed the 2-134 corrosion test. On the basis of numerous 2-134 corrosion test can be produced with uniformity and ease.

aeioa e 24.3% 'minerarlubricating' n and 45p volatile material 2314"gra'm's' of the foregoing" petroleum sulfonic acid "productweref charged to a 3-ne'ck flask fitted with; a: stirrer, and 2,000 grams of naphth'ene' 'baser'lubricatingoil distillate having an SUS'vis'cosity' 'at:100 -F. ofabout" 390 were addeditogether with: 500 .cc. of anhydrous methyl alcohol; The mixture was stirred-and heatedto 113 F., andithenia solution,of-376 gramsof barium hydroxide" in 3,000" cc. of anhydrous methyl alcoholtwas added in three portions: The quantity ofibariurn-hydroxide was in excess of the v calculatedf'amount to produce the basic barium" sulfonate-salt; The resulting: mixture was'theritheated'furthertodistill oif methylalco holandwater, and the'tem-perature Washeld at 338-365 F; for 1 /2 hoursx Anysmall amount of remaining water in the reaction mixture-was then remoyed by "sweeping with nitrogen: The dried mixtureivasthcn'filtered throueh a body of solid filter aid material while-hot; and 195 grams additional. of: the" naphthene base lubricating oil were-added'in' order to bring the active material to concentration. Analysis of the resulting lubricating oilconcentrate vof the basic barium The-weightratio of barium to' sulfur'in the'active materialcalcu-latedto 4.27, whichis substantially theoreticaliorl the true-basic barium sulfohate. In the following Table IV, the figuresgiven for weight per cent of the basic barium sulfonate are those for theconc'entrate; consequen'tly'the weight per cent of theactive basicsulfonateis /4"0f*the1isted figures= In order to illustratetheresultsobtained With othertypes of syntheticlubricant bases, the fol-- lowing Table IV sets forth the results secured witiithe-foregoi-ng basic barium sulfonate additive-and also thecommercial Santolube 203A in a 3:1 lithiumsoap ofhydrogenated castor oillithium stearategrease using a3z1 mixture of di- Z-ethyl hexyl azelate-paraffin base mineral lubrieating oil as the lubricant base, and containing 0.5 phenyl alphanaphthylamine.

Y Tablelll' 2f134 Corrosion Test Additive Weight Percent Copper Grease Result 1. BasicBa'Su-lfonate 1.o% slight'stainzl Slight piuk.; as. 2;BasiciBa*Su.lonatev(3.0%) c Unchauged;-. Unchanged. Do. 3.;Santolube 203A (1%) Very .s1igh-t-; .Slight pink. Do.

sta n 4. "Santolube 203Ai (2%) doc..i do Do. 5. Santolube 203A (3%)L--- Unchanged" Unchanged" Do.

EXAMPLE-5'.

The following example illustrates the preparation of a'r'fapproximately 6,000 pound plant batch of lithium base grease in accordance with the present -invention.h were as riollowszr Weight in Perceutby Emma: pounds Weight Hydrogenated Castor Oil.-' v.' 786 12,,68 Triple Pressed .Stearic Acid 262'. 4. 21 Lithium Hydroxide Mdnohydrate n; 199; 8' 323 Water (Distilledbr Condensed Steam) a 1,779.? Parafiin Base -Minera1 Lubricating. Oil i t y when S US 'viscos'ityat100 F; of ior 1, 213 19. er Di-Yreth'yI he'xyl sebacatesnunui. 3,165.4 58.183 Phenyl alphanaphthylamine 309. Y, 0. 50 D'ye 0.211 Santolube 203A: 61;;8; 1.:00,

The hydrogenated castori. oil in V molten. form was added} to the kttle with stirringtogether with about 483: pounds'(i6l.5t% voi the hydrogem ated castoroil i charee). 0f 1the-minerallubricating oil. Theioilis maintained. less. than.v the amount of hydrogenated castor oil at this sta e in order to promote proper conditioning orthe soap,baseduringlater stages. of the manufacturing; procedurea .With. Ithe kettle contents being stirred at a temperature of; about -200.? va quantity of water. which :WELS :less than ,the quantity-of; hydrogenatemcastdr oilfchargeu (in this case about 56l5'%-,of the hydrogenated :castor oil) was. added, andtheir: the lithium hydroxide; in the form of a..10%., aqueous solution. was introduced The amount of lithium hydroxide; was calculated to betsufiieientior, saponification ,.of all the fatty material. andlto provide a calculated excess of aboutv 046%j lithium 'hydlioxidfi fi ured on the-basis of finishedLgrease-at .18 Zifsjoapv content. Saponification was efiected during aid-hour period of stirring at a temperature 0fj1'80 -200 F with shots of water. being added fromctime vto time to assist. the .-reaction. The stearic acid was then introduced and stirring continued atthe foregoing temperature for aboutillhour with addi-tionalshots. of water being added to prevent the soap base; from; balling. up, and becoming gummy. Thetemperature was.v then raised as quickly as. possiblerto, 3207-3305? andmaint'ained at, the elevated temperaturemfor. a. period: 015-9 hours.;f.0r dehydrationand until thesioa'pibase became: translucentiand hadla tendency -to Jfracturer when cold.v Theremaining mineral lubricating oi-l wasthen introduced slowly. as the temperature dropped to. 300 E. The di-tz-ethylhexyl sebacateintroduction,Was then begun and.con-, tinned: slowly oyer, a period of about 8 hours as thetemperature droppedto about 2720JF. and the desired grease, consistencywas attained. The phenyl alphanaphthylamine, the dye, and finally the JSantolube 203A- were added with, continued stirring and the grease; wasfinally; drawnat a temperaturet-oilfi0el90f FL,

"Iypical. tests: obtained: on: the-vforeg oingygrease wereasiollowsz. 7 r y Penetratiom A STM at 77 workedinnn t 294 Low temperature torque 67 F:, 2,000 gram centimeter-torque;

secs. per revolution 2.4

Thea-ingredients. employed As shown by the foregoing tests and others not listed, the said grease satisfactorily met all of the requirements of U. S. 2-134 and AN-G-25 specifications.

It will be understood that the grease may also contain other additives in small proportions which are compatible with the essential ingredients and do not interfere with the desirable properties thereof. Such additional additives include extreme pressure or lubricity agents, such as dibenzyl disulfide, viscosity index improving and pour depressant type materials such as acrylic acid ester polymers, materials for improving resistance in the salt spray humidity cabinet test such as sorbitan mono-oleate, and the like.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A lubricating grease composition comprisin as the essential constituents an oleaginous liquid lubricating base as the major constituent, about 10-30% by weight of a lithium soap of a saturated soap-forming fatty material, and from 0.25 to 3% by weight of an oil-soluble basic alkaline earth metal salt of a sulfonated hydrocarbon wherein the weight ratio of alkaline earth metal to sulfur content is from 1.1 to 2 times that represented by the normal salt M(SO3R)2, where M is the alkaline earth metal and R is the hydrocarbon residue, said basic salt being in sufiicient proportion to enable said grease composition to pass the copper corrosiontest of U. S. Army specification 2-134.

2. A lubricating grease composition according to claim 1, wherein said basic salt is a basic barium sulfonate.

3. A lubricating grease composition comprising as the essential and at least major proportion of the lubricating base an oil-soluble high molecular weight high-boiling liquid aliphatic dicarboxylic acid ester within the lubricating viscosity range and possessing lubricating properties, sufiicient lithium soap of soap-forming fatty material to thicken said lubricant base, said soapforming fatty material consisting of mor than 50% by weight of a hydroxy soap-forming fatty material selected from the group consisting of hydroxy fatty acids and hydroxy fatty acid glycerides, and from 0.25 to 3% by weight based on said composition of an oil-soluble basic alkaline earth metal salt of a sulfonated hydrocarbon wherein the weight ratio of alkaline earth metal to sulfur content is from 1.1 to 2 times that represented by the normal salt M(SO3R)2, where M is the alkaline earth metal and R is the hydrocarbon residue, said basic s'alt being in sufficient amount to enable said grease composition to pass the copper corrosion test of U. S. Army specification 2-134. V 4. A lubricating-grease composition according to claim 3, wherein said basic salt is a basic barium sulfonate.

5. A lubricating grease composition according to claim 4, which contains about 0.05-1.0% free alkalinity calculated as lithium hydroxide.

6. A lubricating grease composition according to claim 5, wherein the said basic salt is a basic barium sulfonate present in an amount of about by weight.

7. A lubricating grease composition comprising as the lubricant base a minor proportion of mineral lubricatingoil and a major proportion of a branched chain aliphatic diester of a dicarboxylic acid selected from the group consisting of sebacic, azelaic and adipic acids, about 10-30% by weight based on the composition of lithium soap of a mixture of a major proportion of hydrogenated castor oil and a minor proportion of stearic acid, and from 0.25 to 3% by weight based on said composition of an oil-soluble basic alkaline earth metal salt of a sulfonated hydrocarbon wherein the weight ratio of alkaline earth metal to sulfur content is from 1.1 to 2 times that represented by the normal salt M(SO3R)2, where M is the alkaline earth metal and R is the hydrocarbon residue, said basic salt being in suificient amount to enable said grease composition to pass the copper corrosion test of U. S. Army specification 2-134.

8. A lubricating grease composition according to claim -7 which contains about 0.15-1.0% free alkalinity calculated as lithium hydroxide.

9. A lubricating grease composition according to claim 8, wherein the said basic salt is a basic barium sulfonate present in an amount of about Off-2% by weight.

10. A lubricating grease composition according to claim 9, wherein the branched chain aliphatic di-ester is the ethyl hexyl di-ester.

11. A lubricating grease composition consisting essentially of the following ingredients in per cent by Weight:

Di-2-ethyl hexyl sebacate 40-80 Mineral lubricating oil 8-35 Lithium soap of hydrogenated castor oil 8-22 Lithium stearate 3-10 Glycerin 0.7-2.5 Free alkali as LiOH 0.05-1.0 Basic barium sulfonate 0.5-3.0 Oxidation inhibitor 0.2-2.0

12. A lubricating grease composition consisting essentially of the following ingredients in per cent of Weight:

An approximately 3: 1 mixture of di-2-ethyl hexyl sebacate and mineral lubricating oil 60-86 Lithium soap of an approximately 3: 1 mixture of hydrogenated castor oil and stearic acid 12-30 Glycerine 0.7-2.5 Free alkali as LiOH 0.2-0.6 Basic barium sulfonate 0.7-2.0 Phenyl alphanaphthylamine 0.2-1.0

GEORGE W. ECKERT.

REFERENCES CITED The following references are oi. record in the file of this patent:

UNITED STATES PATENT Number Name Date 2,352,811 Swenson July 4, 1944 2,450,221 Ashburn et al Sept. 28, 1948 2,487,080 Swenson Nov. 8, 1949 2,562,814 OHalloran July 31, 1951 OTHER REFERENCES Hain et al., Synthetic Low Temperature Greases from Aliphatic Diesters, article in Ind. and Eng. Chem, vol. 39, April,1947,,pp. 500-506. 

1. A LUBRICATING GREASE COMPOSITION COMPRISING AS THE ESSENTIAL CONSTITUENTS AN OLEAGINOUS LIQUID LUBRICATING BASE AS THE MAJOR CONSTITUENT, ABOUT 10-30% BY WEIGHT OF A LIGHIUM SOAP OF A SATURATED SOAP-FORMING FATTY MATERIAL, AND FROM 0.25 TO 3% BY WEIGHT OF AN OIL-SOLUBLE BASIC ALKALINE EARTH METAL SALT OF A SULFONATED HYDROCARBON WHEREIN THE WEIGHT RATIO OF ALKALINE EARTH METAL TO SULFUR CONTENT IS FROM 1.1 TO 2 TIMES THE REPRESENTED BY THE NORMAL SALT M(SO3R)2, WHERE M IS THE ALKALINE EARTH METAL AND R IS THE HYDROCARBON RESIDUE, SAID BASIC SALT BEING IN SUFFICIENT PROPORTION TO ENABLE SAID GREASE COMPOSITION TO PASS THE COPPER CORROSION TEST OF U. S. ARMY SPECIFICATION 2-134. 